Starting apparatus for internal combustion engines



Feb. 3, 1959 J. RAVER' 2,371,708

STARTING APPARATUS FOR INTERNAL COMBUSTION ENGINES Filed Nov. 22, 1955INV TOR. law: aver HIS ATTORNEY that theentire starting current nitSTARTING APPARATUS FOR INTERNAL COMBUSTION ENGINES Louis J. Raver,Anderson, Ind., assignor to General Motors Corporation, Detroit, Mich.,a corporation of Delaware Application November 22, 1955, Serial No.548,349

3 Claims. (Cl. 74--6) engagement with the flywheel gear of the engine tobe started and an over-running clutch is provided to connect the motorwith the pinion to crank the engine and to permit the pinion to over-runthe motor, when the engine becomes self-operative. The type ofover-running clutch contemplated in the present invention is the one-waytype which will provide a driving connection when the parts are rotatedin one direction and will not transmit torque when certain of the partsare rotated in the opposite direction. A clutch of this type, which isfrequently used, is one which comprises a driven member which isoperatively connected with the pinion and which has an externalcylindrical surface and a driving member connected with the electricmotor which is located without the driven member which has a pluralityof roller camming surfaces in recesses, each of which cooperates withthe cylindrical surface of the driven member and a roller to transmitthe movement of the driving member to the driven member in one directionof rotation only.

When the engine becomes self-operative, the'driven member is rotatedfaster by the engine than the driving member is rotated by the electricmotor. When this occurs, the driven member tends to over-run the drivingmember and each roller tends to move toward the widest portion of itsrecess against a force of a Spring which normally tends to urge theroller into the narrowest portion of the recess. A clutch of the typeherein contemplated is more particularly set forth in the patent toCritchfield 2,211,053, which has been assigned to the assignee of thepresent invention.

It has been found that over-running clutches of the type referred to donot always release, particularly in the event of backfire of theinternal combustion engine. It has been further found that on theoccasion of backfire, severe stresses are imposed upon the startingapparatus and frequently the clutch member, the starter and the startershaft are severely damaged. Further, it has been noted that damage hasoccurred to the entire starting apparatus which includes the electricwindings of the starter, the starter shaft and the clutch parts, whenthe apparatus is used, for some reason with an engine that requires anexceptionally high starting torque. For example, under extremely lowtemperatures, the engine may be almost immovable, and, after thestarting apparatus is actuated so the pinion gear engages the ring gear,the starter will cease to rotate in spite of the fact is imposed overthe wind- States are ice ings of a starter. This may cause the windingsto quickly burn out or cause the rollers of the clutch to Brinell theroller recesses.

The present invention is directed to remedy the above difficulties andit is an object of the present invention to limit the transmission oftorque between the cranking motor and the internal combustion enginewhich is to be started. This object is accomplished by providing aoneway clutch mechanism of a starter drive with a means that will breakthe driving connection between the pinion and cranking motor wheneverthe torque forces applied on the clutch exceed a predetermined value.

Another object of the present invention is to reduce the probability ofdamage to the pinion gear, the oneway clutch drive, and the parts of thestarting motor in a starting motor apparatus for an internal combustionengine by providing a device which will limit the torque which can beapplied on the clutch mechanism of the starting apparatus.

A further object of the present invention is to provide the drivingmember of a roller-type one-way clutch with ratchet teeth and to drivesaid member with a spring biased driving member which has teeth whichmate with the teeth on the clutch member as long as the torque betweenthe members is less than a predetermined value.

It is a still further object of the present invention to utilize aplurality of Belleville type spring members to maintain the drivingconnection between two driving members which have ratchet teeth arrangedso that the driving connection between the members will be brokenwhenever the torque transmitted through the teeth causes the teeth toride upon one another and compress the Belleville springs.

Further objects and advantages of the present inven tion will beapparent from the following description, reference being had to theaccompanying drawings wherein preferred embodiments of the presentinvention are clearly shown.

In the drawings:

Figure l is a longitudinal sectional view of the starter drive accordingto the present invention with the parts in the normal position.

Figure 2 is a longitudinal sectional view of the starter drive in Figure1 showing the arrangement of the parts when the members are subjected toexcess torque.

Figure 3 starter drive showing particularly the shape and arrangement ofthe torque limiting teeth.

In the drawings, and in Figure 1 particularly, the oneway clutch driveof the starting apparatus according to the present invention, includes asleeve 20 rotatable on a smooth surface of a starter shaft, not shown,through longitudinally spaced bearings 22. This sleeve haslongitudinally extending splines 24 on its outer surface whereon apinion 26 may longitudinally move and be rotated. A shift collar 28 hasinternal longitudinally extending splines 30 which are received by asplined surface portion 30a of the starter shaft 3%, which is connectedto be driven by the usual electric motor 31. The shift collar 28 isarranged to be longitudinally moved along the splines of the startershaft by a lever which is not shown and which has a bifurcated end withpins which are received in the annular groove 32 of the collar as setforth in the patent to Critchfield supra. The collar 28 also hasexternal splines 34 on its external surface, the purpose of which willbe hereinafter set forth. v

A ring or a driven member 36 is suitably secured, as by welding orbrazing, to the sleeve 20. This ring 36 is provided with an externalcylindrical surface 38. Interposed between the ring 36 and pinion 26 isa helical spring 40. This spring 40 has one end seated and held inposition relative to the pinion 26 by a spring retainer is a sectionalview of one of the parts of the 42; and has the other end maintained inposition relative to the sleeve 20 and ring 36 by a spring retainer 44.The retainer 44 is provided with a longitudinally extending portion 46,the purpose of which will be hereinafter set forth. A stop. 48. isprovided and suitably secured to the end of sleeve 20 to limit thetravel of pinion 26 on sleeve 20.

The clutch member of the present invention also has a ring or drivingmember 50. This ring 59 is provided with a plurality ofcircumferentially located recesses, not shown, and which are describedmore fully in the Critchfield reference. These recesses are shaped toreceive rollers 5.2 which will transmit torque between ring 50 and ring36 when the rings 50 and 36 are rotated in one direction and will nottransmit torque when either of the members are rotated in the oppositedirection. Interposed between collar 28 and rings 36 and t) and rollers52 is an annular member 54 which is held in position by a snap ring 56and which helps maintain the rollers 52 in proper position relative torings 36 and 5t).

Surrounding the splined portion 34 of collar 28 is an annular member 58which is also a driving member. This member 58 is provided with aninternally splined surface 60 so it may longitudinally move relative tocollar 28 and be rotatable therewith. The member 53 is provided with aserrated surface which is preferably formed as shown in Figure 3 to haveteeth 62 shaped so the member may ratchet in either direction ofrotation. These teeth are adapted to mate with correspondingly shapedteeth 64 which are suitably located on ring, or driving, member 50 toprovide a driving connection between the annular member 28 and ring 59.In connection with teeth 62 and 64, it is to be noted that in the eventa high torque is to be transmitted, the particular shape of the inclinedsurfaces thereof will cause the surfaces to ride upon each other, as inFigure 2, and tend to cause a separation of the two members 50' and 53which is utilized in the present invention to limit the torque betweenthe driving members 51 and 58. Surrounding the parts of the torquetransmitting device as shown and annular member 58 and ring 50 is anouter shell 66. The shell has one end crimped over member 53 andconstantly urges the annular member 58 to the right as in Figure 1 sothat teeth 62 and 64 are normally maintained in engagement with eachother. The shell 66 itself is urged to the right through the action of aplurality of Belleville type springs 63 which are held in position by awasher 70, a washer 72 and a snap ring 74. The washer 7t), spring 68,and washer '72 are annular in shape and are further maintained inposition by the longitudinally extending portion of spring seat 46.

With the above parts in mind, the operation of the torque transmittingdevice as shown in the drawings will now be described. When the engineis to be started, the shift lever, not shown, will cause collar 28 tomove to the right. The movement to the right of the collar will causethe pinion 26 and sleeve 26 to also be moved to the right so that thepinion is moved into engagement with the ring gear or" the engine, notshown. in the event that the pinion 26 passes directly into engagementwith the teeth of the ring gear, the spring 46 will not be compressed.When, however, interference occurs between the gear teeth of the pinion26 and the ring gear, spring 40 will be compressed until the parts ofthe clutch are rotated a sufiicient amount so that the compression ofspring 40 will cause the pinion 26 to snap forward into its engagingposition with the ring gear. The rotation of collar 28 through splines39 is transmitted through splines 60, annular member 58, teeth 62 and toring member 50. When ring member St? is rotated, in the properdirection, the rollers 52 will wedge in the recesses and transmitrotation to ring 36 which is secured to sleeve 29 so that the rotationwill be further transmitted through .the splines24 to pinion 26 to causethe engine to be ro- 4 tated. In the event of backfire of the engine,the pinion 26 will be caused to rotate faster than the collar 28. Whenthis occurs, normally the rollers 5'2 Will cease to transmit rotationbetween rings 36 and 59. In the event that the torque imposed by thebackfire stresses is severe, the teeth 62 and 64, because of theirparticular shape, will cause annular member 58 to move on splines 66 tothe left, as in Figure 2, against the compression forces asserted by theBelleville springs 68 and shell 66 and the driving connection betweenring 5t and the collar 28 will be completely broken. In the event theengine requires a high torque to achieve starting rotation, as when theengine is subjected to extreme cold or has its parts frozen for someother reason, the excess torque applied on collar to the annular member58 will cause the gear teeth to separate against the force exerted bythe Belleville springs 68 so that the starter will rotate independentlyof the pinion 26 without damage to the starter.

From the above, it is manifest that the driving connection, according tothe present invention, will protect the starter apparatus in both theconditions of extreme backfire or under conditions which require extremetorque for starting. Obviously, the amount of torque which will betransmitted between the parts is limited by the strength of theBelleville springs and that these springs may be selected for theparticular application involved. Further, the present invention might beused with other types of one-way clutch mechanisms as, for example, asprag type clutch and will limit the torque which will be applied to thesprag members and the other parts of the starting mechanisms.

While the embodiments of the present invention as herein disclosedconstitute preferred forms, it is to be understood that other formsmight be adopted.

What is claimed is as follows:

1. In a starting apparatus for an internal combustion engine, thecombination comprising; an electric motor, a pinion movable into meshwith a gear of the engine to be started, a sleeve having internal andexternal splines for moving the pinion, a one-way over-running clutchfor transmitting cranking torque between the motor and pinion to crankthe engine and permit the pinion to over-run the motor when the enginebecomes selfoperative, said clutch having an inside cylindrical memberconnected with the pinion, an outside clutch cam member, intermediaterollers adapted to become wedged between cam surfaces of the outsideclutch cam mem her and the cylindrical surface of the inside clutchmemher to drive the pinion when cranking the engine and adapted inconjunction with the outside cam member to be released when the enginebecomes self-operative, an annular member having splines on its inneropening adapted to slide on the external splines of the sleeve means,mating teeth on the annular member and outside clutch member, and ameans for maintaining the teeth in mating engagement with each otherwhen torque between the motor and engine is less than a predeterminedvalue.

2. In a starting apparatus for an internal combustion engine, thecombination comprising; an electric motor, a pinion movable into meshwith a gear of the engine to be started, a sleeve having internal andexternal splines for moving the pinion, a one-way over-running clutchfor transmitting cranking torque between the motor and pinion to crankthe engine and permit the pinion to over-run the motor when the enginebecomes self-operative, said clutch having an inside cylindrical memberconnected with the pinion, an outside clutch cam member, intermediaterollers adapted to become wedged between cam surfaces of the outsideclutch cam member and the cylindrical surface of the inside clutchmember to drive thepinion when cranking the engine and adapted in conunction with the outside cam member to be released when the enginebecomes self-operative, an an. nular member having splines on its inneropening adapted to slide on the external splines of the sleeve means,mating teeth on the annular member and outside clutch member, and ameans for maintaining the teeth in mating engagement with each otherwhen torque between the motor and engine is less than a predeterminedvalue, said means including an outer sleeve forming an enclosure forsaid clutch having one end in engagement with said annular member andresilient means between said clutch member and sleeve.

3. In a starting apparatus for an internal combustion engine, thecombination comprising; an electric motor, a pinion movable into meshwith a gear of the engine to be started, a sleeve having internal andexternal splines for moving the pinion, a one-way over-running clutchfor transmitting cranking torque between the motor and pinion to crankthe engine and permit the pinion to over-run the motor when the enginebecomes self-operative, said clutch having an inside cylindrical memberconnected with the pinion, an outside clutch cam member, intermediaterollers adapted to become wedged between cam surfaces of the outsideclutch cam member and the cylindrical surface of the inside clutchmember to drive the pinion when cranking the engine and adapted inconjunction with the outside cam member to be released when the enginebecomes self-operative, an annular member having splines on its inneropening adapted to slide on the external splines of the sleeve means,mating two-way ratchet teeth on the annular member and outside clutchmember, and a means for maintaining the teeth in mating engagement witheach other when torque between the motor and engine is less than apredetermined value.

Richards May 13, 1930 Miller May 22, 1951

